Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in JAVA):

Solution:
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int h = sc.nextInt();
        int w = sc.nextInt();
        
        // board[i][j]: 迷路
        char[][] board = new char[h][w];
        for (int i = 0; i < h; i++) {
            String str = sc.next();
            for (int j = 0; j < w; j++) {
                board[i][j] = str.charAt(j);
            }
        }
        
        // visited[i][j]: 当該マスを既に通ったか否か
        boolean[][] visited = new boolean[h][w];
        
        // 上下左右
        int[] dx = new int[]{1, 0, -1, 0};
        int[] dy = new int[]{0, 1, 0, -1};
        
        // steps = BFS((0, 0)→(h, w)までの最短経路の深さ)
        int steps = -1;
        Queue<int[]> que = new ArrayDeque<int[]>();
        que.add(new int[]{0, 0, 0});
        while (!que.isEmpty()) {
            int[] cur = que.poll();
            int x = cur[0];
            int y = cur[1];
            int depth = cur[2];
            
            if (x == h - 1 && y == w - 1) {
                steps = depth;
                break;
            }
            
            // 移動可能ならそのマスに深さ+1を配ってキューに入れる
            for (int k = 0; k < 4; k++) {
                int nx = x + dx[k];
                int ny = y + dy[k];
                int ndepth = depth + 1;
                
                if (0 <= nx && nx < h && 0 <= ny && ny < w &&
                    board[nx][ny] == '.' && !visited[nx][ny]) {
                    que.add(new int[]{nx, ny, ndepth});
                    visited[nx][ny] = true;
                }
            }
        }
        if (steps == -1) {
            System.out.println(-1);
            return;
        }
        
        // ans = 通行不能にしてもよいマス数
        // a = 全マス数, b = 通行に必要なマス数, c = 既に通行不能なマス数
        int ans = 0;
        int a = 0, b = 0, c = 0;
        a = h * w;
        b = steps + 1;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                if (board[i][j] == '#') {
                    c++;
                }
            }
        }
        ans = a - b - c;
        System.out.println(ans);
    }
}